1. Field of Invention
The present invention relates to wheelchairs, and is more particularly concerned with a wheelchair having apparatus affixed thereto for enabling the wheelchair to ascend and descend stairways.
2. Prior Art
Many forms of inventions have been disclosed in the Prior Art for enabling a wheelchair to climb stairs or other objects.
Brown et al., U.S. Pat. No. 3,283,839, shows an arrangement for a stair-climbing wheelchair utilizing two driven spiders having three wheels driven by a chain. However, there is no belt over the three wheels. Also, the lower spider containing a plurality of wheels is not driven but only dragged along. Further, there is no means shown for driving the arrangement. Certainly, there is no apparatus shown for permitting the occupant to direct and propel the apparatus himself. Winsor, U.S. Pat. No. 4,044,850, shows only a straight tractor tread for driving the wheelchair. An electric motor is shown to be the sole driving force. Rasmussen, U.S. Pat. No. 4,154,315, shows a spider having five wheels with a belt driving the wheels by means of a motor. Bihler et al., U.S. Pat. No. 4,556,229, shows an independent support for a wheelchair with the belt driven by an electric motor. Auer, U.S. Pat. No. 4,627,508, also shows a separate belt-driven vehicle utilizing an electric motor. Hester, U.S. Pat. No. 4,645,222, shows a wheelchair having a plurality of spiders with wheels, but driven by an electric motor. Livingston, U.S. Pat. No. 4,960,180, shows a separate cart using an endless track, to which the wheelchair is clamped. The device may be motor-driven or hand-operated by an attendant. Misawa, U.S. Pat. No. 5,197,558, teaches a motor-driven wheelchair carrier to which a wheelchair may be clamped. Finally Lepek, U.S. Pat. No. 5,273,296, shows a vehicle utilizing a plurality of spiders and wheels for overcoming rough terrain. A wheelchair is mentioned among the vehicles which may be utilized.
It is clear that none of the references shows a wheelchair capable of ascending and descending stairways, in which the sole motive power for engaging the stair-climbing apparatus, and for ascending and descending, is provided by the muscular power of the occupant of the wheelchair.